1. Field of the Invention
The invention relates to a method of forming V-grooved sheet metal pulleys from flat sheet metal discs. More particularly, the invention relates to a method of roller spinning and splitting a dynamically balanced V-grooved pulley in which an annular radially extending flange is roller spun in a cup-shaped stage blank formed from the disc and subsequently split to form the pulley V-groove. Furthermore, the produced pulley may be provided with a reinforced hub flange wall without attaching additional reinforcing means thereto, as heretofore required.
2. Description of the Prior Art
Many procedures have been used and are known for the formation of V-grooved sheet metal pulleys from flat sheet metal discs. Many of these procedures involve stamping and drawing operations to produce at least the cup-shaped blanks from which the V-grooved pulleys are subsequently roller spun. Examples of such stamping and drawing operations are shown in U.S. Pat. Nos. 2,493,053 and 3,080,644.
Finished V-grooved pulleys or the cup-shaped stage blanks for subsequent spinning into V-grooved pulleys which are produced by such prior stamping and drawing methods, are not balanced dynamically since the pulleys and blanks are formed by a series of progressive die steps on a non-rotating blank.
Other procedures and apparatus have been known for directly spinning cup blanks and V-grooved pulleys from flat metal discs for producing dynamically balanced pulleys, as shown in U.S. Pat. Nos. 1,680,061 and 1,728,002. The equipment and dies required, however, involve headstock dies with sliding and movable members which considerably increase the cost of pulley manufacture with such apparatus. Likewise, these dies require means on the machine for controlling movement of the die components which contribute to the increased costs and involve maintenance problems. Also, considerable tooling costs are involved to provide various dies from which to produce a variety of cup blanks, since a different die size and configuration is required for each type of cup blank produced.
Such prior art equipment and processes appear to be satisfactory for their intended use especially where vast quantities of cup-shaped blanks and finished spun products are made at high production rates. Such vast quantities spread the cost of the equipment, die and tooling which is expensive, over the large number of units produced. It is desirable in certain situations and locations to be able to produce a relatively small quantity of spun V-grooved pulleys directly from flat sheet metal discs with inexpensive, low volume producing equipment and methods. Furthermore, it is desirable to be able to change the size and configuration of the V-grooved pulley produced with a minimum tooling cost, so that small quantities of various sizes and configurations of pulleys can be produced by relatively low initial and replacement costs for equipment, tooling and dies.
One type of V-grooved pulley commonly produced by various stamping, drawing and spinning procedures and combinations thereof, has a flat bottom wall or hub flange portion which is connected with a generally cylindrical side wall, which in turn terminates in a pair of outwardly extending annular flanges to form the pulley V-groove. Heretofore, pulley constructions having such elongated cylindrical hub portions have been produced by roller spinning the V-groove in the generally cylindrical side wall, which had been formed by stamping and drawing procedures, as shown in U.S. Pat. No. 2,567,334.
Many applications using such elongated hubbed pulleys require a reinforced circular bottom wall for mounting a hub on the pulley, where the pulley will experience high torques and forces on the hub area. Prior pulley hub flange walls are reinforced by welding an outer concentric cup-shaped blank on the hub flange wall area of the pulley to increase the thickness of the hub flange wall without increasing the thickness of the cylindrical side wall where such reinforcement is not required. Other constructions such as shown in U.S. Pat. No. 2,729,110 telescopically secure a second cup-shaped blank within the main outer cup-shaped shell or blank to achieve the desired thickness. Various other known pulley constructions use an enlarged hub which forms the entire bottom wall of the pulley and is joined directly to the cylindrical side wall, as shown in U.S. Pat. No. 1,680,061.
Most of these prior pulley constructions having a reinforced hub area require additional components or procedures, such as welding, which increases the cost of the pulley.
Splitting of disc-shaped blanks and of cup-shaped blanks is another procedure well known in the art of pulley manufacture to produce a V-grooved pulley, as shown in U.S. Pat. Nos. 1,555,771, 3,087,531, and 3,225,425. Pulleys produced by such known methods and procedures have no generally cylindrical side wall extending between the hub flange wall and the V-groove flanges when produced directly from a flat disc without previously working the same as shown in U.S. Pat. Nos. 1,555,771 and 3,225,425. Also, those pulley blanks having cylindrical side wall portions which terminate in outer annular flanges which are split to form a V-groove have been formed by stamping and drawing procedure, and have a cylindrical side wall thickness equal to the thickness of the hub flange wall. Such pulleys, thus, may not be dynamically balanced and require additional manufacturing procedures and components to reinforce the hub flange wall, where the hub flange wall requires a greater thickness than the thickness of the cylindrical side wall.
No known method of which I am aware enables the production of relatively small quantities of various sizes and configurations of V-grooved pulleys by roller spinning and splitting flat sheet metal discs on usual and simple types of metal spinning machines; which V-grooved pulleys are dynamically balanced due to their complete formations by roller spinning and splitting; and in which the hub flange wall is connected to the V-groove by a generally cylindrical side wall which may be formed thinner than the hub flange wall permitting a pulley to be produced having a thick reinforced hub flange wall and thinner side wall without requiring additional components and manufacturing procedures and excess metal.